1. Field of the Invention
The present invention relates to an outboard motor configured to supply outside water drawn in through a water pump to an engine and other heat-generating components for the purpose of using the water to cool the engine and the other heat-generating components of the outboard motor.
2. Description of the Related Art
In a conventional outboard motor, a water pump is placed near a lower portion of a casing and driven by a drive shaft for transmitting engine output to a propeller. An intake hole is provided in a casing below a waterline. When the water pump is activated, outside water is drawn in from the intake hole and sucked into the water pump. The water that has been sucked into the water pump travels through a cooling water conduit member, which is made of metal and arranged to extend upward in the casing, and is supplied to the engine (see JP-B-3745470 and JP-B-3509171, for example).
However, various components such as the drive shaft, a transmission, an oil pan, and an expansion chamber are housed in the casing. Thus, in order to avoid interference with the above components, a bore diameter of the cooling water conduit member cannot be set large enough. Consequently, discharging performance of the water pump is sacrificed.
In addition, since the cooling water conduit member runs near or inside the expansion chamber, there is a concern about deterioration of both the cooling water conduit member and a sealing member for the cooling water conduit member due to high exhaust heat and exhaust components.